1. Field of the Invention
The present invention relates to a hose connector, and in particular to a hose connector specially adapted for use with soft-walled hoses.
2. Description of the Prior Art
Hose connectors for such use have been disclosed, for example, in U.S. Pat. No. 3,167,331, British patent No. 960,436, German patent No. 1,072,028 and German utility models Nos. 18 24 206 and 296 05 218, whose registration dates have been published but which are not printed publications.
In these hose connectors, compression coil springs are bent into an annular shape for use as tensioning elements to form a toroidal coil spring. Common to the enumerated disclosures is the principle that a divergent internal conical wall of a collar surrounding an end of a hose into which a tubular nipple is inserted radially presses the toroidal coil spring arranged between the conical collar wall and the hose end against the hose end and thus firmly holds the hose end on the inserted tubular nipple when a sleeve is threadedly connected to the collar. According to German utility model No. 18 24 206, the tubular nipple end inserted into the hose has shallow grooves delimited by rounded shoulders merging into the smooth circumferential surface of the tubular nipple end. The rounded groove shoulders do not contribute to the fluid-tightness of the connector and are provided apparently to facilitate pulling the hose end, which is under pressure, off the nipple.
Although some of these disclosures go back to the 1950s and 1960s and appear to provide ideal and simple fixing devices, they have not found a commercial market. This may be explained by recent tests (see German utility model No. 296 05 218) showing that the known screwed-together hose connectors are not sufficiently fluid-tight and the hose end cannot be readily pulled off these connectors. In addition, the toroidal coil spring is only radially pressed against the hose end, which means that radial resistance of the hose material is rapidly encountered when the collar and sleeve are screwed together so that it cannot be readily felt whether the end of the hose actually is sufficiently firmly held on the nipple.
In all the hose connectors of this general type, it was apparently assumed that pressing the hose end against the inserted tubular nipple end will automatically assure sufficient fluid-tightness and, at the same time, that orienting the internal conical wall portion of the collar so that it diverges in the direction of pulling the hose end over the nipple end will assure that the toroidal coil spring is ever more firmly wedged against the hose end as it tends to pull off the nipple end, which makes it unnecessary to impart a special profile to the tubular nipple end to prevent a tendency of the hose end to be pulled off the nipple end.